ᐅ Insulating a slanted wall / cavity in front of or behind insulation
Created on: 5 Apr 2021 16:41
S
stephax
Hello,
I am currently renovating our garden shed (wooden structure), which we recently acquired and had to completely gut first.
Now I have a question about insulation, as I have the following fundamental problem:
Unfortunately, the exterior walls are completely uneven—both in the floor plan lines and vertically. For the interior cladding, I need to build a furring strip framework that is straight. However, this will result in gaps between the interior wall cladding and the exterior wall varying from 8 cm to 22 cm (3 inches to 9 inches).
My question: Is it better to install the insulation directly against the exterior wall or directly against the interior wall cladding? In other words, where is it smarter to leave the cavity due to the varying distance? Most walls and ceilings only allow for insulation up to 8 cm (3 inches) thick. This would mean that, with the uneven walls, there could be up to 14 cm (5 ½ inches) of air between the insulation and the interior or exterior wall...
If necessary, here is some additional information:
The exterior walls are constructed from inside to outside as follows: wooden battens, expanded polystyrene (EPS), roofing felt, tongue-and-groove cladding. Inside, I plan to install a vapor retarder over the insulation and then cover the wall with 12 mm (½ inch) plywood panels.
Thank you for your suggestions and recommendations.
I am currently renovating our garden shed (wooden structure), which we recently acquired and had to completely gut first.
Now I have a question about insulation, as I have the following fundamental problem:
Unfortunately, the exterior walls are completely uneven—both in the floor plan lines and vertically. For the interior cladding, I need to build a furring strip framework that is straight. However, this will result in gaps between the interior wall cladding and the exterior wall varying from 8 cm to 22 cm (3 inches to 9 inches).
My question: Is it better to install the insulation directly against the exterior wall or directly against the interior wall cladding? In other words, where is it smarter to leave the cavity due to the varying distance? Most walls and ceilings only allow for insulation up to 8 cm (3 inches) thick. This would mean that, with the uneven walls, there could be up to 14 cm (5 ½ inches) of air between the insulation and the interior or exterior wall...
If necessary, here is some additional information:
The exterior walls are constructed from inside to outside as follows: wooden battens, expanded polystyrene (EPS), roofing felt, tongue-and-groove cladding. Inside, I plan to install a vapor retarder over the insulation and then cover the wall with 12 mm (½ inch) plywood panels.
Thank you for your suggestions and recommendations.
Since we are currently dealing with this topic as well, here is my current understanding:
HausiKlausi is right; in general, exterior insulation is preferable to interior insulation – it is less prone to errors, often cheaper, and does not reduce living space.
Opinions on interior insulation vary greatly – sometimes dramatically 😀 But what they all have in common is either a ventilated double-layer construction or a cavity-free single-layer interior insulation using capillary-active insulating materials, such as calcium silicate boards or Multipor.
This is especially important if the rooms are often or continuously heated (possibly even damp rooms) and condensation may occur inside the wall structure, particularly in winter. If it is just a simple shed, you can deviate from the usual setup.
By the way: the wall construction can be well simulated with ubakus. Unfortunately, the program does not yet understand "capillary-active" insulation materials, so do not be discouraged if it shows a condensation issue for Multipor, for example. However, the program handles ventilated constructions well 😉
HausiKlausi is right; in general, exterior insulation is preferable to interior insulation – it is less prone to errors, often cheaper, and does not reduce living space.
Opinions on interior insulation vary greatly – sometimes dramatically 😀 But what they all have in common is either a ventilated double-layer construction or a cavity-free single-layer interior insulation using capillary-active insulating materials, such as calcium silicate boards or Multipor.
This is especially important if the rooms are often or continuously heated (possibly even damp rooms) and condensation may occur inside the wall structure, particularly in winter. If it is just a simple shed, you can deviate from the usual setup.
By the way: the wall construction can be well simulated with ubakus. Unfortunately, the program does not yet understand "capillary-active" insulation materials, so do not be discouraged if it shows a condensation issue for Multipor, for example. However, the program handles ventilated constructions well 😉
stephax schrieb:
then cover the wall with 12mm (1/2 inch) multiplex plywood" 🙂Multiplex plywood and moisture are not exactly a great combination.
Well, with interior insulation, there will be a dew point inside the insulation during winter because warm air holds more moisture than cold air. A vapor barrier would prevent this, but only if it is 100% airtight. Since this is usually difficult or nearly impossible to achieve, interior insulation is generally not recommended.
However, the current construction with wooden battens, polystyrene, roofing felt, and tongue-and-groove cladding is not ideal either. Condensation will likely occur somewhere around the polystyrene and roofing felt (layman’s opinion!) when it’s 20°C (68°F) inside and 0°C (32°F) outside.
I’m not sure to what extent this causes significant damage to a garden shed that may only be used and heated occasionally during winter. Probably less so. Have you mentioned how the building will be used?
But maybe a professional will come by 🙂
However, the current construction with wooden battens, polystyrene, roofing felt, and tongue-and-groove cladding is not ideal either. Condensation will likely occur somewhere around the polystyrene and roofing felt (layman’s opinion!) when it’s 20°C (68°F) inside and 0°C (32°F) outside.
I’m not sure to what extent this causes significant damage to a garden shed that may only be used and heated occasionally during winter. Probably less so. Have you mentioned how the building will be used?
But maybe a professional will come by 🙂
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